Increased motion of the air and/or fuel charge injected into an engine combustion chamber can increase combustion efficiency under some conditions. For example, charge motion can increase the effectiveness of combustion by introducing air velocity in directions perpendicular to the flow direction. By introducing additional kinetic energy into the combustion chambers, the ignition front may traverse the volume of the combustion chamber more quickly and more evenly so as to interact with a heightened amount of fuel before thermal energy is translated to piston motion. Further, resulting turbulence may increase homogenation of the air-to-fuel mixture within the combustion chamber.
Charge motion control valves (CMCV's) may be used to induce desired turbulence by restricting a portion of the intake passage within the intake manifold. Upon passing through this restriction, air is reflected from the far wall with a horizontal velocity as well as its initial vertical (flow-direction) velocity induced by a pressure differential in the intake system. CMCV's may be controlled by an actuator programmed to create this obstruction during certain, advantageous, operating conditions.
CMCV's may be implemented in a plate-shaft rotation configuration wherein the plate face has a geometry designed to cover a substantial portion of the cross-sectional area of the intake passage when aligned perpendicularly to stream flow, called the fully closed position. In the fully open position the plate may rotate about its shaft such that the width of the plate and shaft obstruct the air passage, allowing substantially more air to pass through. The rotating shafts are generally located through an axis of symmetry on the plate's face or at an edge of the plate adjacent to one wall of the passage.
However, the inventors herein have recognized that in high load situations, the amount of air delivered to the cylinders for combustion acts as a limiting factor for engine power. Likewise, attempts to address this have placed the valve further upstream in a wider portion of the intake passage, but this loss in proximity to the cylinder head port creates losses in the control and effectiveness of the turbulence achievable by the CMCV.
One approach to address this apparent paradox is to configure the intake manifold's ports with outlets aligned to a common head plane and incorporate a rotatable valve (such as a CMCV) with an axis of rotation recessed within an inner wall and a welded connection encircling each intake port upstream of the axis. This may be achieved by integrating the valve into the intake manifold's port during the welding of the intake manifold, for example.
In this way, the proximity to the cylinder head may be preserved without overly restricting the air flow for combustion. Here the CMCV has a shaft housing or “cartridge” around the shaft and the plate projects from this housing. In this implementation, the housing can be inserted into a depression in the intake manifold during the welding of the first and second shells nearest the intake passage. By this method, the CMCV allows unobstructed air flow when not in use thus reducing engine power losses.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.